1. Field of the Invention
The present invention relates generally to an automatic machine, and more particularly to a suction device, which sucks various sizes of objects and has a function of preventing air leakage to increase the efficiency of suction.
2. Description of the Related Art
A conventional suction device has a substrate having a plurality of apertures. Objects for work are put on the substrate and the air below the substrate is extracted to provide a condition of the atmospheric pressure above the substrate much greater than the atmospheric pressure below the substrate. Therefore, the objects are sucked on the substrate firmly for work.
The conventional suction device must arrange the apertures just meeting the sizes and the sharps of the objects to make the objects sealing all the apertures, such that the suction device has a well efficiency of suction. If there is one ore more apertures not sealed, the air above the substrate flows through the substrate via the unsealed aperture and we call that “air leakage”. If there is air leakage occurred, the suction device has a poor capacity of suction to hold the objects on the substrate.